In early 2009, a woman died of the flu in eastern China. Although tragic for her and her family, particularly in light of her being only 27 years old, there was nothing particularly unusual in that. This time, though, was different. The virus that killed her was the H5N1 bird flu virus and, although millions of chickens are infected with the virus every year, it had rarely been transmitted to humans. Following this case, however, the World Health Organisation warned that the virus had become highly contagious and could become a global pandemic – a terrifying prospect given that the mortality rate for human cases of H5N1 is 60%.
All eyes turned to CSL and the world's other large vaccine makers, including GlaxoSmithKline and Sanofi Pasteur. CSL has had an H5N1 vaccine approved since 2008, but as flu viruses continually mutate the stock quickly goes out of date.